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#pragma once
#include <type_traits>
#include <lib/modernjson/detail/meta/void_t.hpp>
// http://en.cppreference.com/w/cpp/experimental/is_detected
namespace nlohmann
{
namespace detail
{
struct nonesuch
{
nonesuch() = delete;
~nonesuch() = delete;
nonesuch(nonesuch const&) = delete;
void operator=(nonesuch const&) = delete;
};
template <class Default,
class AlwaysVoid,
template <class...> class Op,
class... Args>
struct detector
{
using value_t = std::false_type;
using type = Default;
};
template <class Default, template <class...> class Op, class... Args>
struct detector<Default, void_t<Op<Args...>>, Op, Args...>
{
using value_t = std::true_type;
using type = Op<Args...>;
};
template <template <class...> class Op, class... Args>
using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
template <template <class...> class Op, class... Args>
using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
template <class Default, template <class...> class Op, class... Args>
using detected_or = detector<Default, void, Op, Args...>;
template <class Default, template <class...> class Op, class... Args>
using detected_or_t = typename detected_or<Default, Op, Args...>::type;
template <class Expected, template <class...> class Op, class... Args>
using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
template <class To, template <class...> class Op, class... Args>
using is_detected_convertible =
std::is_convertible<detected_t<Op, Args...>, To>;
} // namespace detail
} // namespace nlohmann
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